Swisstopo Topographic Map of Switzerland
Below is a Swisstopo (the Swiss equivalent of the OS) topographic map of Switzerland.
Nov-18 Not working
Swisstopo's map tileserver has a usage limit per domain name, but it can only handle 2-part domain names, e.g. walkingclub.ch, not 3-part ones like walkingclub.org.uk
Below is OpenStreetMap instead